Conventionally, in creating a design instruction to design a printed circuit board on a circuit design step, a circuit designer has been supposed to write the design instruction in handwriting, and instruction required in designing has been communicated from the circuit designer to a printed circuit board designer by passing the completed design instruction to the printed circuit board designer.
Herein, the design instruction describes which portion of a circuit diagram should fall under the instruction, and in such occasion, the circuit designer was supposed to add items such as the names of parts and wirings (parts location “reference”, part numbers, net names, etc.) to the design instruction in handwriting.
However, instruction was not fully communicated in communication operation by such a design instruction, and further, in the case where the circuit diagram was changed, the names of parts and wirings described on the design instruction needed to be changed in accordance with the change of circuit diagram.
For this reason, in the above-described conventional method, writing and changing work to the design instruction became complicated, and there was a possibility of miswriting the names of parts and wirings, and furthermore, there was the first problem that a problem occurred or quality was deteriorated due to insufficient communication on written instruction.
Further, regarding the design quality of a designed printed circuit board, a design instruction itself depends on designers, so that its quality varies according to the skill of designers, and there was the second problem that instruction contents were affected by instruction designers such that printed circuit board design quality is deteriorated due to human-dependent situation.
Meanwhile, there is known a resistance called a damping resistance with several tens Ω, which is serially inserted into a signal line for the purpose of removing noise from reflected waves, and such a damping resistance is frequently used for the output of a buffer circuit, the output of a driving IC for a memory, or the like.
Conventionally, in extracting a damping resistance from the circuit diagram, attribute of the resistance, information of a connected item, connection status and the like have been visually confirmed on the circuit diagram. Specifically, there are many areas where the damping resistance must be extracted from the circuit diagram visually, and it was difficult to judge by anyone but the designer himself/herself.
Then, in designing printed circuit board, although it is necessary to instruct which resistance is the damping resistance by using the position and the wiring method of damping resistance as a circuit board design instruction, enormous time was required in extracting the damping resistance because no condition existed in extracting the damping resistance.
In short, the design instruction for the damping resistance is necessary in designing printed circuit board and checking printed circuit board, but there was the third problem that enormous time was required in extracting the damping resistance itself.
Furthermore, the number of LSIs to be mounted increases as a circuit size becomes larger, and the increase of LSIs directly connected to the increase of the number of bypass capacitors.
With the increase of the bypass capacitors, there was the fourth problem that much labor and time cost was consumed in recognizing as many as several hundred bypass capacitors, for example, by using a screen of CAD system and a drawing of layout, which was drawn on paper.
The bypass capacitors are classified by functions caused by the use methods (parts to be connected) of the capacitors, and the bypass capacitors cannot be judged on single capacitors.
To extract the bypass capacitors from the circuit diagram, information of connected parts, connection status and the like on the circuit diagram were visually confirmed. Specifically, there was no final judgment other than a method of directly confirming to a designer himself/herself.
It is to be noted that there is a method of applying attribute into the bypass capacitors in designing a circuit, but load in designing becomes heavier and such method was difficult to be realized.
Specifically, design instruction for bypass capacitors is necessary in designing printed circuit board and checking printed circuit board, and there was the fifth problem that enormous time was required in extracting bypass capacitors.
In addition, extracting items (circuit parts, wirings, etc.) on a circuit diagram as one group by their types and functions and dividing them into groups in order to reflect them on a design instruction in basic designing or creating a check list of a circuit diagram were necessary on making instruction and checking.
Conventionally, search processing has been done for each item (parts, wiring information, etc.) in extracting the groups, enormous time was required in extracting work in proportion to the article quantity of items and parts quantity, and further, extracted data are inherent to the circuit diagram, so that there was the sixth problem that workload and much time in proportion to items were required such that the same extracting work was necessary in another circuit diagram.
Furthermore, in confirming a printed circuit board, which was designed by a printed circuit board design system, for the instruction of a design instruction in high-density and high-speed circuit design of a printed circuit board, associated instruction items were confirmed and inspected and were done manually for corresponding portions, by using search functions of a circuit design system and a printed circuit board design system.
Specifically, because of reasons such as sudden increase of the difficulty level of design caused by digitalization and the difficulty of maintaining the integrity of an entire system by the shortened competitiveness of products or multi-function, the reasons such as the design quality dependent on designers, labor spent in drawing check and corrected instruction is enormous, and shortening the labor has been the key to shorten the lead time of design.
For this reason, there was the seventh problem that the work efficiency deteriorated and enormous labor and cost were required in inspection, confirmation, and drawing check regarding a designed printed circuit board or creating a correction instruction.
Meanwhile, electronic equipment manufacturers have a large number of design conditions and instructions of noise measures, heat measures and the like, which they have been cultivated by conventional product development, in the developing process of new products, such design conditions were instructed to printed circuit board designers before designing a printed circuit board, and the printed circuit board designers designed the printed circuit board according to the instructions.
Then, a prototype of the printed circuit board is formed after the design of the printed circuit board is completed, but before that, verification work whether the design instructions were properly followed were done.
Herein, since some design instructions have rules that cannot be expressed in numerical values, there were cases where automatic check using a CAD system could not be performed, and check for such portions had to be done visually.
Such visual check starts by searching areas in the circuit diagram and the printed circuit board, which correspond to the design instruction, and a search function or the like of the CAD system is used in searching the corresponding areas. To use the function, it is necessary to operate both the circuit diagram and the printed circuit board, and furthermore, since there are cases where articles that must be checked are several hundred or more depending on a product, there was the eighth problem that enormous labor and time were required in check.
Further, conventionally, when visually checking items on a printed circuit board of high-density multiple layer, in order to clearly display contents to be checked, setting for displaying the check contents by taking the interrelation of associated items in consideration has been done manually while the check contents were accurately grasped.
Specifically, if the contents to be checked are not clearly displayed, there is a possibility that the check contents are misrecognized and accurate check cannot be performed.
There was the ninth problem that the work of performing display control every time to prevent misrecognition depended on the skill of operators and it caused significant loss of time.
Furthermore, even if an instruction is given in designing printed circuit board, such instruction contains contents whose quality cannot be maintained unless the circuit board is designed accompanied by knowledge such as experience and logic.
Conventionally, the designer of printed circuit board has needed to search and read books and materials of corresponding technical information in order to understand the instruction, and there was the tenth problem that the designer of printed circuit board needed to spend enormous time in searching and reading the technical information.
It is to be noted that prior art that the applicant of the present invention knows when filing an application for patent is an art described above but not an invention disclosed in documents publicly known, so that there is no prior art information to be described.